Subspeciation in the Ruby-throated Bulbul Rubigula dispar

Abstract

Summary. Ruby-throated Bulbul Rubigula dispar, currently Vulnerable on the IUCN Red List owing to trade pressure, is considered monotypic across its range on three Sundaic islands in Indonesia: Sumatra, Java and Bali. However, examination of photographs and museum specimen labels and measurement of 37 Sumatran and 50 Javan specimens indicate that birds from Sumatra differ from those on Java (type locality) and Bali in exhibiting a variably red (not pale yellow) iris and a slightly longer bill and wing. Consequently, we propose subspecies rank for the Sumatran population. We recommend that the two taxa be maintained pure in captivity and that any releases of confiscated birds take place on the correct island based on eye colour.